Skip to content

TracePrint

Print every sub-expression used while evaluating an expression and return the result of the evaluation. Each step is wrapped in HoldCompleteForm and indented by one space per level of the evaluation, so nested computations are visibly deeper than their enclosing ones.

$ wo 'TracePrint[2 + 3]'
 HoldCompleteForm[2 + 3]
  HoldCompleteForm[Plus]
  HoldCompleteForm[2]
  HoldCompleteForm[3]
 HoldCompleteForm[5]
5

$ wo 'TracePrint[2^3 + 5]'
 HoldCompleteForm[2^3 + 5]
  HoldCompleteForm[Plus]
  HoldCompleteForm[2^3]
   HoldCompleteForm[Power]
   HoldCompleteForm[2]
   HoldCompleteForm[3]
  HoldCompleteForm[8]
  HoldCompleteForm[5]
 HoldCompleteForm[8 + 5]
 HoldCompleteForm[13]
13

A second argument restricts the printing to sub-expressions matching the given pattern:

$ wo 'TracePrint[2^3 + 5, _Integer]'
   HoldCompleteForm[2]
   HoldCompleteForm[3]
  HoldCompleteForm[8]
  HoldCompleteForm[5]
 HoldCompleteForm[13]
13